Mobile eXtensible Music Format (mXMF) is a 3GPP-approved open standards format that bundles standard MIDI along with custom instruments (Mobile DLS) into one file. Mobile XMF is a version of eXtensible Music Format (XMF) specifically designed for mobile devices. XMF takes the benefits of MIDI and adds the power of custom instrument design and synthesis. Mobile XMF is a container format that usually includes a MIDI file and a Mobile DLS file. A Mobile XMF file allows the combined playback of a device’s embedded 128 General MIDI (GM) instruments along with custom instruments, only custom instruments, or only the embedded 128 GM instruments. Since it is designed specifically for mobile devices, Mobile XMF also retains any channel priority information found in the MIDI file.



Mobile DLS (mDLS) is also an open standards 3GPP-approved format for MIDI-controllable instruments, specifically designed for mobile devices. Mobile DLS is very similar to DLS-2, the format for MIDI-controlled instruments used by many PC soundcards and operating systems. Mobile DLS instruments are usually "played" by bundling them with MIDI into either Mobile XMF files or XMF files.



Mobile DLS technology offers many additional benefits to standard MIDI.

The most significant are:

  • Playback consistency across devices

    • The nature of MIDI—the fact that it is only a ‘score’ and relies on the instruments embedded in the device that’s playing it—provides for high levels of expression with very small file size cost. However, as content producers know well, the trade-off is the loss of control over the actual sound of the instruments playing the score. Mobile DLS solves this problem with the ability to include one’s own flute to be played by a MIDI score. This guarantees that not only the MIDI notes will sound the same on all devices but that the flute’s tone or timbre will also be unchanged from device to device.

  • Musical instruments beyond the General MIDI 128

    • Most MIDI devices contain only the 128 instruments required by General MIDI (from #0, Grand Piano to #127, Gun Shot). Mobile DLS technology allows for the creation of MIDI-based content which contains instruments and sounds not found in the standard 128 General MIDI instruments. MIDI information could be packaged together with an authentic Brazilian berimbau or an Indian tabla Mobile DLS instrument to create compelling localized game audio or ringtone content.

  • Highly-controllable sound effects

    • Using Mobile DLS in mobile games can be especially powerful because of the importance of minimizing file size as well as processing power. For example, consider designing the sound of footsteps for a game character. Accomplishing this using a digital audio recording would require a file that includes variations in the pitch and volume of each footstep for maximum realism . A character walking six steps down a hall would require an even longer file or at the least, one audio file would need to be triggered three times. Such audio files would quickly consume valuable file size.

    Using Mobile DLS, one footstep sample can be played at different pitches, tempos, and volumes to emulate a variety of footsteps (those of a running giant or walking child, for example) for only the size cost of one sample, articulation, and minimal MIDI data.



    Faith Technologies’ mXMFTool allows for both the creation of Mobile DLS and Mobile XMF content and is free for download. Use it by importing sound samples, adding synthesis techniques, and creating Mobile DLS custom MIDI-controlled instruments for use in ringtones, mobile games and other applications. The tool also allows for the creation of Mobile XMF content by packaging Mobile DLS along with MIDI or SP-MIDI, allowing the MIDI to play one’s own custom instruments instead of a phone’s built-in General MIDI instruments. mXMFTool can be used to create just one of these Mobile XMF files at a time or instantly create an entire new library of content using the batch conversion feature. Additionally, the tool is optimized for use with the Qualcomm® CMX™ multimedia engine. The tool can be used to check compatibility with CMX phones as well as preview your content and know how it will sound on CMX phones using the CMX emulator.



    Faith West has created a library of 125 Mobile Downloadable Sounds (mDLS) designed specifically for use in mobile games. The Game Sound Collection offers a large range of high-quality custom instruments including animal noises, human actions sounds, sports sound effects, weapons, vehicular, and environmental sounds, all in standard Mobile DLS format. This collection is included in Qualcomm®’s CMX Studio® authoring tool as well as Faith Technologies’ mXMFTool. It can also be downloaded on it’s own from the link below. These sounds can be used freely by any developer in commercial applications as is or with your own custom modifications.



    Click here to download the free mXMFTool.

    Click here to download the free Mobile DLS Game Sounds Collection.

    For more information on the mobile XMF Technology and how to author mobile DLS for CMX 4.4, we recommend downloading Using Mobile DLS and Mobile XMF with CMX 4 4